How much do you feed a 12 week old?

I've struggled a lot with breast feeding because my milk never came in (I've tried everything) and trying to figure out how much to feed/supplement my baby. I think I've been overfeeding him, and now I'm concerned I'm under feeding him because I think it was too much. (And I feel like a failure for not having sufficiently learned all of his cues)

I go back to work on Monday and don't know how much to tell the caregiver or how frequently. I've tried asking the doctor and lactation and I can't get an answer. I can't use 2.5 times his body weight because it would be way too much food.

He'll be 12 weeks on Monday. How many ounces do you give per bottle and how frequently for when your baby was/is 12 weeks?

What time of day was the first and what time the last?

Do you give the same number of ounces at every feeding?

Thanks!